class Solution {
    public List<String> readBinaryWatch(int num) {
        List<String> resList = new ArrayList<>();
        for (int i = 0; i < 12; ++i)
            for (int j = 0; j < 60; ++j)
                if (Integer.bitCount((i << 6) | j) == num)
                    resList.add(i + ":" + (j > 9 ? "" : "0") + j);
        return resList;
    }
}
